Absorption refrigeration



Nov. 22, 1960 w. G. KOGEL ABsoRPTIoN REFRIGERATION 2 Sheets-Sheet 1Filed Nov. 12, 1958 INVENTOR.

Nov. 22, 1960 `w. G. KOGEL 2,960,842

ABSORPTION REFRIGERATION Filed Nov. 12, 1958 2 Sheets-Sheet 2 {w/XMUnited States Patent ABSORPTION REFRIGERATION Wilhelm Georg Kagel,Stockholm, Sweden, assignor to Aktiebolaget Electrolux, Stockholm,Sweden, a corporation of Sweden My invention relates to absorptionrefrigeration sys- `tems of the kind in which vapor is expelled out ofsolution by heating.

It is an object of my invention to provide for absorption refrigerationsystems of this type an improvement for eficiently utilizing the heatsupplied to the vapor expulsion unit of the system.

Another object of the invention is to recirculate a part of theabsorption solution in its circuit to make use of heat supplied to thevapor expulsion unit of the system which otherwise would be lost. Iaccomplish this by diverting absorption solution from its path of flowfrom a place of vapor expulsion to a place of absorption, and returningthe diverted solution to the place of vapor expulsion. At the place ofvapor expulsion I utilize heat which otherwise would be lost to raisethe diverted solution from one level to a higher level by vapor-liquidlift action. The raised solution is mixed with absorption solution fromwhich vapor has been expelled at the place of Vapor expulsion, and themixture is conducted in the aforementioned path of flow from the placeof vapor expulsion to the place of absorption. Absorption solution isdiverted from this path of flow from the mixture, s that a portion ofthe absorption solution is constantly recirculated through the place ofvapor expulsion and never reaches the place of absorption.

rPhe invention, together with the above and other objects and advantagesthereof, will be more fully understood upon reference to the followingdescription and the accompanying drawing forming a part of tl'nsspecitication, and in which Pig. l illustrates more or lessdigrammatically an absorption liquid circuit of absorption refrigerationapparatus embodying the invention;

.and Fig. 2 is a view of refrigeration apparatus like that shown in Fig.l illustrating another embodiment of the invention.

In the drawing, the invention is embodied in absorption refrigerationapparatus of a uniform pressure type containing an inert pressureequalizing gas. Refrigerant vapor is expelled from absorption liquid ina generator or vapor expulsion unit by heating and passes through aconduit 11 to a condenser. The refrigerant vapor, such as ammonia, isliquefied in the condenser and ows into an evaporator in which theliquid refrigerant evaporates and diffuses into an inert gas, such ashydrogen, to produce a refrigerating etfect. The resulting gas mixtureof refrigerant and inert gas flows from the evaporator to an absorberwhich may be of an air-cooled type including a coil 12 and an absorbervessel 14, such gas entering the absorber vessel ythrough a conduit 15.

In the absorber refrigerant is absorbed from the gas mixture intoabsorption liquid, such as water, which is delivered thereto through aconduit 16, and the abducted through a conduit 18 andinner pipe 19. of aliq- 5,-;

2,960,842 Patented Nov. 22`

uid heat exchanger 20 to the generator 10. The weakened absorptionliquid from which refrigerant vapor been expelled is conducted from thegenerator through the outer passage 21 of the liquid heat exchanger 20and the conduit 16 to the absorber to absorb refrigerant vapor. ln orderto simplify the drawing, the condenser, evaporator and connectionstherefore have not been shown, such parts being well known and theirillustration not being necessary for an understanding of my in lvention.

The generator 10 comprises an open-ended heating tube or flue pipe 22which may be heated in any suitable manner, as by an electrical heatingelement or a gas or liquid fuel burner, for example, which projects itsflame into the lower end of the flue. A boiler pipe 23 and vafrrce Yporlift pipe or tube 24 extend axially of the heating flue 22 and aresecured at 25 and 26, |respectvely, t the outer surface of the flue ingoo-d thermal contact therewith, as by welding.

The liquid heat exchanger 20 in the form of (a coil is disposedconcentrically about the flue pipe 22 and the upper end 19a ofthe innerpipe or passage 19 thereof is connected to the boiler pipe 22 at aregion 27 below the liquid surface level maintained in the absorbervessel 14. The upper part of the boiler pipe 23 is out of thermalcontact with the flue pipe 22 and at its upp'cfr end is connected to astandpipe 28 whose upper exten'- sion forms the conduit 11 through whichexpelled vapor passes to the condenser, as previously explained.

-To lthe lower closed end of the boiler pipe 23 is corinected the lowerend of the vapor liftV tube 24 which is in thermal contact at 26 withthe flue pipe 22; The upper end of the vapor lift tube 24 communicateswith the upper end of the vertically disposed standpipe 28 which isconnected at its lower end to the outer passage 21 of the liquid heatexchanger 20. s

The parts of the generator just described and liquid heat exchanger 20are embedded in suitable insulating material 29 contained within a metalcasing or shell-30 having openings at the top and bottom through which'the open ends of the llue pipe 22 project.

Heating of the ltube or tlue 22 heats the boiler pipe 23 in thermalcontact therewith to heat the enriched absorption solution in the pipe23 to the boiling temperature and cause expulsion of refrigerant vaporfrom the absorption liquid. Liquid of decreasing concentration flowsdownwardly in the pipe 23 and passes into the vapor lift tube 24.Heating of the tube or flue pipe 22 effectively heats the absorptionliquid in the vapor lift tube 24 and causes expulsion of vapor therefrom.to raise liquid by vapor-liquid lift action into the upper part of thestandpipe 28. v

Absorption liquid weak in refrigerant flows from the bottom of thestandpipe 28 through the outer passageV 2 1 of liquid heat exchanger 2t)and conduit 16 tothe upper part of the absorber coil 12, as previouslyexplained. l 'A When the refrigeration apparatus just describedisoperated with an electrical heating element, which may be in the form ofa cartridge housing a Wire or the like having a relatively highresistance that generates heat when connected to a source of electricalsupply, such heating element desirably is inserted within the bottompart l22a of the heating tube. The bottom and top parts 22a and 22b ofthe heating tube or flue are connected `to one another in such a way, asby a few spot welds indicateda't 3l, that a poor thermal conductive pathis provided therebetween. In this way, the bulk of the heatV generatedby the electrical heating element is effectively utilized along avertically extending zone'which is co-exte'nsive with the thermalconnections 25 and. 26 between'the .heatingtube and the `boiler pipeand' vapor-liquid tube, and the heat loss resulting from heat owing tothe fop part 22b of the heating tube is at a minimum.

When the refrigeration apparatus just described is operated-with a gasor liquid fuel burner, on the other hand, the hotproducts ,of combustionVof the burner darne passing Hthrough the heatingtube or ue notonlyfheatthe bottom Hue part 22a but also the top flue part 22b whichrepresents a heat loss.

YIn accordance with my invention, in order to utilize effectively thehot products of combustion passing through `theheating llue 22 when therefrigerationapparatus of .Fig/.lis operated'with ajuid fuelrburner,heat available at the top ue part 22b is employed to heat weak ab-Vsoption liquid flowing froxnthe Vvapor expulsion unit 10. ln Fig. 1apart of the absorption liquid weak in refrigerant and owingdownwardlyin the outer passage 21 of liquid heat exchanger is diverted into avertically dis- .posed tube 32 which is vheat conductively connected at33,

as'fby welding, to the top `part 22b of the heating tube o ue.

The hotrabsorption liquid weak-in refrigerant andowing from standpipe 28into the upper section of liquid heat exchanger 20 gives up some of itsheat to absorption .liquid rich in refrigerant and flowing through theinner Iliquidheatexchanger passage 19 to 'the boiler pipe 23. vAftersuch heat exchange has been effected between absorption liquid weak andrich in refrigerant, respectively, a part of the weak absorption liquidis diverted into the tube 32 in which liquid therein is heated by the-top part Y 22b-of the -heating tube or flue. Vapor is expelled from`liquid Y intube 32 Lto lift or raise liquid therein by vaporliquid liftaction, such raised liquid being conducted. to the top part of thestandpipe 28 to which the upper rend Of" tube 32 is connected.

. V'I'heconduit ortube 32 essentially `serves as a by-pass r`in a partofthe absorption solutionrcircuit in which someV `of theabsorptionliquid is continuously being recirculated [to extract as much heat aspossible from the heating gases passing through the heating tube or flue21. In this way, the heating gases discharged from the upper end of thev`heatingilue 22 will be atV the lowest temperature possible;

and the heat losses, that is, heat conducted axially up- Vvward in thetop flue part 221; and heat conducted radially therefrom through theinsulation 29, will be at a minimum.

v The vapor lift tube 24 lifts liquid from the level A in V boiler pipe23 to the level B in standpipe 28 from which liquid flows by gravity tothe upper part of the'absorber coil 12. It will be seen that liquid isdiverted into the Yloweiend of tube 32 froma region of the outer passage321 of liquid Vheat exchanger 20 which is below therliquid surface levelB in standpipe 28 to which absorption Ysoluition Vis raised through thevapor lift tube 24. Diverted liquidis raised to the upper partof-standpipe 28 through 'the tube 32 in a path of flow which may bereferredvto kas a yby-pass and is separate from the circuit in which'solutionris normally circulated through andbetween the .plac'e of`vaporexpulsion and place of absorption. Since the liquid level B in standpipe28 yis a relatively short v`distance below the region towhich kliquid israised in Vthe vapor lift Vtube 32, it is not necessary to expel a con-"siderable quantityk of vapor from liquid in tube 32 to t:effect liftingof liquid by vapor-lift action under the infle'xc'ejoffthe reaction headformed by the liquid colin the standpipe 28. Accordingly, the t-op part22b 'O'fthe heating tube is primarily utilizedto expel refrigerant vaporfrom solution in the lift tubev32, the quantity ofabs'orption liquidvapor that is expelled from solution -bei'n'gvat alrninimuims'o that theconcentration of refriger.. antfinthe absorption solution passing from:the lower en'd Y `ofstandpipe 28 .willbe reduced further.

f gtureiofjthe liquidupassing .fromlthe standpipe-ZS .into

4 increasing the temperature head of weak absorption liquid flowing invthermal exchange relation with rich absorption liquid and Veffecting anincrease in temperature of lthe rich absorption liquid introduced intothe boiler pipe 23.

In Fig. 2 I have shown another embodiment of the invention in which'likeparts are .designated by the same reference numeral with added thereto.In Fig. 2, absorption liquid rich in refrigerant ows from absorbervessel 114 through conduit 118, .the inner passage 119 of liquid heatexchanger and connection 11911 to generator pipe 123. The extreme lowerend of pipe 123 is in communication with the lower end of pump pipe orvapor lift tubef124 lwhich .is heat conductively connected at 126 to theheating tube 122. Upward movement is imparted to liquid in the vaporlift pipe 124 by vaporliquid lift action under the influence of areaction head formed by the liquid columnmaintained in pipe 123.

Vapor generated in the vapor lift pipe -124 ows from the upper endthereof through the upper part of standpipe 128 and a conduit 134 Vtoa'region 123g in pipe 123 which serves as an analyzer and is disposedbelow the liquid surface level A of the liquid column contained therein,the liquid level A being essentially the same as the liquid surfacelevel in the absorber vessel 114. VAbsorption liquid from whichrefrigerant vapor hasV been expelled ows by gravity from standpipe 128throughthe outer passage of liquid heat exchanger 120 and conduit116'into the upperpart of the absorber coil 112.

The embodiment of Pig. 2 differs from that of Fig. l described above `inthat all of the vapor expelled from absorption liquid riching/refrigerant is effected in the vapor lift tube or pump pipe 124which is thermally connected at 126 to an intermediate part 122t` of theheating tube or ue having a bottom section 122d which projects throughthe bottom opening in the casing 130 and a top section 122e whichprojects through a top opening in the casing 130. The top and bottom uepipe sections 122:1 and 122e are of larger cross-sectional area than thein- -termediate part 122e and the ends of these flue pipe sectionssnugly iit over the upperV and lower ends, respectively, of theintermediate part 122C.

When the refrigeration apparatus of Fig. 2 is being operatedelectrically, the top and bottom flue pipe sections 122d and 122e arenot needed land the electrical heating cartridge may be positionedwithin the tube part 122e. The top and bottom iiue pipe sections 122dand 122e are employed in the manner shown in Fig, 2 and just describedwhen the refrigeration apparatus is adapted for operation with a uidfuel burner. In such case, a suitable burner may be employed which canbe positioned within the lbottom flue pipe section 122d so that thehighest temperature heating gases will be made available to Veffectheating of the intermediate flue part 122C.

In Fig. 2 a part of the absorption liquid weak in refrigerant isdiverted from the outer passage 121 of liquid heat exchanger'120 into avertical tube 132 which is yconnected at its upper end to the standpipe128. The tube 132 -is heat conductively connected at 133 to the top uepipe section 122e to lift liquid in the tube and continuouslyrecirculate a part of the weak absorption liquid through the standpipe128 in the same manner Y shown in Fig. l and described above.

rabsorption solution is normally circulated in its circuit through andbetween a place of vapor expulsion and a place of absorption, theimprovement which comprises the steps Lof diverting absorption solutionfrom its path -of .-ow in 'which 'solution Jnormally 'flows from the-place ofv vapor-.expulsion :to the-,place of absorption, raising thediverted solution from one level to a higher level by vapor-liquid liftaction at the place of vapor expulsion, mixing such raised divertedsolution With absorption solution at the place of vapor expulsion fromwhich vapor has been expelled, and flowing such mixture in said path ofow in which solution normally flows from the place of vapor expulsion tothe place of absorption, the improvement which comprises divertingsolution from said mixture in said normal path of ow from the place ofvapor expulsion to the place of absorption at a region thereof which isbelow the liquid surface level in said normal path and raising thediverted solution from the one level to the higher level in a by-passwhich is separate from the circuit in which solution is normallycirculated through and between the place of vapor expulsion and place ofabsorption, whereby a portion of the absorption solution is constantlybeing recirculated through the place of vapor expulsion and neverreaches the place of absorption.

2. The improvement set forth in claim l in which circulation ofabsorption solution in its circuit is effected by vapor-liquid liftaction at the place of vapor expulsion by heating gases passing througha rst zone, and in which the diverted solution is raised from the one tothe higher level by vapor-liquid lift action at the place of vaporexpulsion by the same heating gases passing through a second zone afterpassing through said lrst zone.

3. The improvement set forth in claim 2 in which absorption solution inits path of ow to the place of vapor expulsion passes in heat exchangerelation with absorption solution in its normal path of flow from theplace of vapor expulsion, and absorption solution is diverted from itsnormal path of flow from the place of vapor expulsion after passing inheat exchange relation with absorption solution in its path of ow to theplace of vapor expuls1on.

4. In an absorption type refrigerating system comprising an absorptionliquid circuit including a generator and an absorber and rst conduitmeans for conducting liquid from said absorber to said generator andsecond conduit A means for conducting liquid from said generator'to saidabsorber, said generator including a vertically disposed heating tubethrough which a uid heating medium is adapted to pass upwardlytherethrough and a rst vaporliquid lift tube which is thermallyconnected thereto at a rst zone and through which liquid is raised fromone level to a higher level by vapor lift action to maintain a liquidbody having a liquid surface level which will eect circulation of liquidin said circuit, and a connection in said circuit for diverting liquidfrom said second conduit means and conducting such liquid to a regionabove the liquid surface of the liquid body, said connection including asecond vapor-liquid lift tube which is thermally connected to saidheating tube at a second zone which is above said first zone.

5. Apparatus as set forth in claim 4 in which said rst and second zonesof said heating tube have a poor heat conductive connectiontherebetween.

6. Apparatus as set forth in claim 4 in which said rst and secondconduit means are in heat conductive relation in a lengthwise directionto form a liquid heat exchanger, and said connection for divertingliquid from said second conduit means is connected thereto intermediatethe ends of said liquid heat exchanger.

7. Apparatus as set forth in claim 6 in which said generator includes avertically disposed pipe to the upper part of which is connected theupper ends of both of said vapor-liquid lift tubes, the lower `end ofsaid pipe being in communication with said iirst conduit means.

References Cited in the le of this patent UNITED STATES PATENTS Re.18,859 Maiuri June 6, 1933 2,785,543 Kogel Mar. 19, 1957 2,797,557 KogelJuly 2, 1957

